This invention relates to couplers for connecting two shafts together for the purpose of transferring rotational motion from one shaft to the other. The coupler has particular application in the agricultural irrigation field where irrigation pipeline support towers have centrally located drive motors for propelling wheels located at the ends of the towers. The motor's gear box is connected to worm drives at the wheels by drive shafts. Drive couplers are used to connect the drive shaft to both the motor gear box and the worm drives. Of course couplers could also be used in other applications where two generally aligned but spaced shafts have to be connected such that rotational motion of one shaft is transferred to the other. Additionally, it is quite often desirable that the coupler be able to tolerate some degree of misalignment between the shafts. Misalignment usually takes the form of the shafts not being parallel to one another.
The invention is particularly concerned with situations where the ends of the shafts remote from the coupler have to be fixed in position prior to installing the coupler. Accordingly, the shafts have no axial movement and perhaps little or no transverse movement available with the result that the coupler has to be installed generally between and/or around the pre-installed shafts.
Prior art couplers of the above type are known as split couplers and have what might be described as a built-up construction wherein a plurality of arms are placed about the end of a shaft and bolted together. The arms extend beyond the end of the shaft where they intersect with the arms of the opposite shaft or some intervening third part in some sort of engagement. Sometimes a rubber connecting block is involved to accommodate misalignment but this leads to problems with the rubber block adding lots of torsional movement called wind-up, with attendant backlash problems. In addition to wind-up, a major problem with the built-up construction is the high number of components and the large number of fasteners required. The high part count adds to cost and installation time.